1. Field of the Invention
This invention relates to an ion (electron) multiplier for detecting or measuring energy beams of electrons, ions, charge particles, ultraviolet rays, soft X-rays, etc.
2. Related Background Art
As schematically shown in FIG. 1, in an electron multiplier, energy beams, as of electrons or others, impinge on dynodes DY1.about.DY16 of the electron multiplying unit to multiply and emit secondary electrons, and the collecting electrodes (anodes) A collect the emitted secondary electrons for detection.
The electron multiplying units have various types. Commonly quarter-cylindrical dynodes DY1.about.DY16 are substantially alternately arranged in a direction of incidence of energy beams. The arrangement of FIG. 1 is the typical one which is the so-called box-and-grid-type.
Resistors are inserted between the respective dynodes and their adjacent ones. The resistors equidivide a voltage applied between the first-stage dynode DY1 and the final-stage dynode DY16.
This is the basic structure of the electron multipliers. The common assembly of the electron multipliers is shown in FIGS. 2 and 3.
In the electron multiplier of FIGS. 2 and 3, respective dynodes DY are supported, enclosed by respective support frames 1. Each support frame 1 is made of a conducting material and is electrically connected to the associated dynode DY. The electron multiplier further comprises two support rods 3 which are secured to a holder 2 and are parallel with each other. These support rods 3 are inserted in holes 4 of each support frame 1 to support the dynodes by the support rods 3. A gap between each support frame 1 and its adjacent one is retained constant by spacers 5 through which the support rods 3 are inserted.
In this conventional electron multiplier, resistors R are disposed in one row on one of the rows of the dynodes. Leads L of each resistor R are welded respectively to vertically adjacent ones of the support frames 1.
The above-described electron multiplier includes the resistors R arranged in one row on one of the rows of dynodes. This tends to increase a total length of the electron multiplier. To reduce the total length, it is necessary to narrow a gap between the respective resistors and their adjacent ones. But it could adversely cause contact of the leads L of the resistors R to narrow the gap.
The resistors R are supported only by welds of the forward ends of the leads L, which cannot firmly secure the resistors R. It is also a problem that the resistors R totter.